Tokyo - (Business Wire)--Mitsubishi Electric announced today the launch of its 5.7-inch, QVGA color TFT-LCD module with a white LED. This industrial-use model features high brightness, long backlight life and a built-in LED driver in a low power consumption LCD module design. Sale of the module begins on December 1, 2010 on Mitsubishi's website.In recent years, TFT-LCD modules are widely used in a variety of applications such as factory automation, measurement equipment and commercial and industrial inventory control. These applications require modules to be slim, compact, and lightweight, and also call for high brightness with low power consumption and longer operational life. With this addition to its lineup of industrial-use TFT-LCD modules, Mitsubishi Electric aims to meet the needs of its customers.Product Features1) Market-leading long-life backlight with high brightness and low power consumptionAt a temperature of 25 degrees Celsius, the LED backlight has a typical operating life of 100,000 hours450 cd/m2 high brightness for better visibility in bright environmentsTotal power consumption (including backlight) is reduced to 1.83W, which is 44% less than the previous model of AA057QB03.2) Built-in LED driverAn LED driver is built into the module to achieve a more compact design and lower product costHigh-voltage inverter not required3) Slim, lightweight construction design of less than 9mmImproved backlight structure design reduces thickness to 8.8mm, which is 32% thinner than the previous model of AA057QB03Module weight is 165g, which is 14% lighter than the previous model of AA057QB03.4) Environmentally conscious constructionThe TFT-LCD module is fully compliant with the European RoHS directive, and is completely mercury-free. Summary of sale Product Model Luminance (cd/m2) Shipment date Production per month 5.7-inch QVGA TFT-LCD module AA057QD01 450 December 1 3,000 Source: Company, compiled by Digitimes, October 2010 Specifications AA057QD01 Display size (resolution) 5.7-inch (320x240 dots) Display area (mm) 115.2(H)x86.4(V) Number of dots 320(H)x240(V) Pixel pitch (mm) 0.36(H)x0.36(V) Contrast ratio 800:1 Luminance (cd/m2) 450 Viewing angle (CR>10) -80~+80(H) -60~+80(V) Optimum viewing angle (contrast ratio) 6 o'clock Number of colors 262k (6bit/color) Backlight unit LED Electrical interface CMOS Module size (mm) 144.0(W)x104.6(H)x8.8(D) Operation temperature (°C) -30~+80 Storage temperature (°C) -30~+80 Source: Company, compiled by Digitimes, October 2010
Oct. 25, 2010 - Lextar Electronics Corporation reveals today a series of new lighting applications, including the world's first high-efficiency photolithography LED light tube for clean rooms, high-brightness LED light tubes of 2,600 lm, ultra light and bright LED bulbs of 1,000 lm, and CCT adjustable flat panel light. The products will debut at the 2010 Hong Kong International Lighting Fair (Autumn Edition) held at the Hong Kong Convention and Exhibition Center from Oct 27 to 30. These innovative products will demonstrate the diversity of LED products and the technical strength of Lextar.Lextar will display four main series of products: LED light tubes, LED bulbs/downlights, LED panel lights and COB (chip-on-board) light engines.LED light tube seriesIn LED light tubes, Lextar introduces the world's first high-efficiency photolithography LED light tube for clean rooms. The novel product uses a technology that combines a special LED and a specially-made light tube lens with cut-off filters. It can filter wavelengths of less than 500 nm and its efficiency is double that of similar tubes made with amber LED which are currently on the market. It is the ideal lighting product for plants and clean rooms. As plants require long hours of lighting, using LED light tubes can save 50% of energy compared to traditional light tubes. For 24 hours of lighting a day, 100 LED light tubes can save around US$200 a month. It has a life-time of 40,000 hours, which is 7-10 times longer than that of traditional tubes. Another product, a high-brightness high-efficiency LED light tube of 2,600 lm, boasts the efficiency of 100 lm/W, and its high-brightness design extends its application to business environments with high ceilings, such as halls or factories. In addition, Lextar is introducing an ultra light plastic LED tube of 175 g, which is a breakthrough in LED lighting technology by the Lextar R&D team.LED bulb/downlight seriesIn the bulb series, Lextar introduces an ultra light and bright LED bulb of 1,000 lm to replace the traditional 100 W incandescent bulb. Its power consumption of 12W saves up to 88% of energy compared to traditional bulbs. Its non-metallic heat sink reduces the weight to below 140 g, which leads to easier mounting. It establishes a new generation of specifications for LED bulbs in the industry. Lextar is also exhibiting a number of adjustable LED light sources, including a slim designed dimmable downlight module of a 2-cm thickness with a remote control, and a 4.5 W dimmable bulb, which demonstrate Lextar's full range of technology development in LED lighting applications.LED flat panel light seriesWith years of R&D technology in TFT-LCD backlights, Lextar extends the LED backlight technology to lighting products. Lextar is exhibiting a 60 x 60cm CCT adjustable LED flat panel light with a remote control which offers color temperatures ranging from warm white to cool white. The user can adjust the color temperature according to the occasion, time and mood to create difference ambiences. LED panel lights emit a soft light produced by a secondary source. It creates a stable and soothing lighting effect which is suitable for offices, hospitals, schools and shopping centers.COB light engine seriesIn addition to lighting applications, Lextar's COB light engine is a core component in lighting products. Lextar will showcase its mega high brightness 70W COB of 8,000 lm in the exhibition. In addition, COB light engine series of 4W, 6W, 10W, 70W and 100W will be on display in the exhibition, and product application ranges from low-power bulbs to high-power bay lights, street lights, architectural light and more. The features include high stability, long lifespan and multiple applications.Lextar chairman and president David Su, states that the new products revealed at the Hong Kong International Light Fair are comparable to products from international brands in specifications and applications. The innovative products clearly demonstrate Lextar's all-round technology development in the lighting domain. The Lextar lighting R&D team is aggressively developing new technologies in LED lighting sources and light modules. Lextar also offers customized solutions to different markets and clients, including OEM and ODM services for international brands, as well as provides total solutions for light modules.
Chicago - (Business Wire) - NEC Display Solutions of America, a leading provider of commercial LCD display and projector solutions, announced today the new MultiSync EX series ideal for corporate users looking for increased productivity and sleek aesthetics.The introduction of the series begins with the 23-inch MultiSync EX231W, an LED-backlit LCD monitor equipped with DisplayPort and DVI-I for full high-definition resolution. The monitor offers users an ultra slim bezel (14.6mm width), ultra light weight (9.3 lbs. with stand) and USB pass-through on the top of the monitor, which allows quick connecting of a webcam or simple flash drive access. Additionally, its excellent ergonomic features include a fully adjustable stand with 110mm height adjust, pivot, swivel and tilt, as well as a built-in carrying handle and quick release stand, which is ideal in financial applications where multiple monitors are tiled.First-class quality comes in the form of brand new technologies like the human sensor, which detects user activity in front of the monitor and reduces its power up to 95% with inactivity. Users have the ability to adjust the inactivity length and sensor settings. The monitor's ambient light sensor detects external light sources and adjusts the display's brightness accordingly, while its carbon savings meter calculates the reduction of greenhouse gas emissions."Building on the strong heritage of the MultiSync brand, the EX series was developed to give users a unique blend of an ultra-slim, light-weight display that is extremely environmentally friendly and packed with features," said Kevin Christopherson, director of product marketing for desktop monitors at NEC. "The stunning design of the MultiSync EX231W makes it a perfect candidate for corporate and financial users looking for a benchmark product throughout its offices. The innovations built into this product make it our greenest desktop series to date with the least amount of materials, waste and harmful substances."The widescreen MultiSync EX231W offers the following features:1920x1080 full high-definition resolution250 cd/m² brightness25,000:1 dynamic contrast ratio31W typical power consumption, 16W in ECO ModeDisplayPort and DVI-I connectivityUSB pass-through4-way ergonomic stand with 110mm height adjust, pivot, swivel and tiltQuick-release standTouch-sensitive On Screen Display (OSD) controlsHuman sensorAmbient light sensorECO Mode, Carbon footprint meter and cost meterIntelligent Power Management (IPM) system and off timerDynamic Video Mode (standard, text, movie, game photo)External power supply via mini AC adaptorEnergy Star 5.0 complianceWindows 7 and Windows Vista certifiedThe MultiSync EX231W will be available in November 2010 at an estimated street price of US$339 and ships with a 3-year parts and labor limited warranty.NEC Display Solutions of America 23-inch LED monitor, the MultiSync EX231WPhoto: Company
Taiwan's LED production volume ranks number one in the world and the output value comes in second. But lighting makers have had nothing to rely on when developing their LED products because of a lack of common standards at the moment. It will take efforts from the industrial, governmental and academic sectors to work together to establish the standards. According to Taiwan Lighting Fixture Export Association Chairman David Chang, Taiwan used to be the "kingdom of lighting," and had a complete supply chain. Similarly, the LED industry in Taiwan today has a complete supply chain as well, offering an opportunity to reinvent the lighting industry's golden age. Chang, talking about the early development of Taiwan's lighting industry, noted that Taiwan became the "kingdom of lighting" 30 years ago, and the Taiwan Lighting Fixture Export Association was established 21 years ago. The lighting devices at that time were mostly OEM/ODM products for export. There was a complete supply chain formed by upstream, midstream and downstream suppliers, and most of them were small to medium businesses. It was the kind of family business that was usually passed on from one generation to the next. Those companies were very good at cost analysis and hard working, and they had very strong sales from exports mainly to America and Europe. About 11 years ago, the labor structure in Taiwan underwent a major transformation. Labor and land costs both increased. Competition from China-made low-price products forced Taiwan's lighting makers to move their production to China, mostly in Guangdong province. Since then, the lighting industry in Taiwan has become stagnant. In recent years, LED technology has seen some major progress, and new technology has been introduced to the lighting sector. Moreover, optoelectronics players are diversifying into the lighting industry. With help from optoelectronics players, the lighting industry is regaining its strength. But how lighting and optoelectronics players from two different industries can form a synergy is something that needs to be contemplated on. Energy conservation and carbon reduction are international global trends and the global goal is to cut carbon emissions by 48 billion tons by 2050. Lighting is a key factor affecting the environment. For example, lighting generated 19 million tons of carbon emissions globally in 2005, which is equivalent to 70% of the worldwide carbon emissions by small cars. Now incandescent bulbs are being banned gradually worldwide. Finding ways to reduce lighting's impacts on the environment will be an important issue in the future. The areas we can work on include light sources, lighting devices and control systems - all of which should have their efficiency improved. Taiwan is still the leading supplier of LED products in terms of volume and second in terms of value (but the Korean government and companies have been investing heavily in the sector, fast and strong growth can be expected). LED lighting is a very promising industry, and because of improvements in luminous efficiency, LED's luminous efficiency has surpassed all traditional lighting sources in 2010. The age of LED lighting has arrived. However, the development in LED lighting still faces some issues. The LED is a point-source light with low beam and high luminance and without a universal standard. Although LED lighting products are developing quickly, their functions are immature and costs are still high. But general lighting requires comfort, reliability, standardization, better illumination and uniformity, and low costs. Taiwan's LED lighting industry has a complete supply chain, which includes upstream suppliers of LED wafers and chips, midstream suppliers of packaging services, and downstream makers of lighting modules and designers of lighting devices. This is a great advantage. For the future of the LED lighting industry, Taiwan players should promote cooperation with their counterparts from China (but Taiwan's independent operations must be maintained). In practice, Taiwan should establish standards for LED lighting, expand government subsidies, organize regular forums for the lighting industry, and interact with international peers. But with no standards or guidelines for the makers, it is therefore necessary for the industrial, governmental and academic sectors to work closely together. And the lighting and the optoelectronics industries have to form a synergy. David Chang, chairman of Taiwan Lighting Fixture Export AssociationPhoto: Digitimes, October 2010
AMD has introduced the AMD Radeon HD 6800 series, designed specifically for gamers by delivering unprecedented game performance starting at US$179. The new AMD Radeon HD 6800 series graphics cards provide more than 30% greater game performance than competing products, harnessing AMD's second-generation Microsoft DirectX 11-capable architecture, best-in-class energy efficiency, and an unmatched feature set, including AMD Eyefinity multi-display technology.The AMD Radeon HD 6800 series graphics cards also support both DisplayPort 1.2 and HDMI 1.4a, providing PC users with expanded options for multi-monitor configurations, display selection, and new DisplayPort audio features.With the AMD Radeon HD 6800 series graphics cards, AMD is introducing AMD HD3D technology, the result of the company's open 3D initiative for stereo 3D gaming and movies. AMD HD3D technology supports over 400 titles through its partners, and AMD's open 3D ecosystem approach encourages the broadest selection of 3D solutions, available at the most affordable cost.The AMD Radeon HD 6800 series graphics cards is also fully supporting both DirectCompute and OpenCL, ensuring broad application support.The AMD Radeon HD 6800 series graphics cards is supported by a dozen add-in-board companies, including Asustek Computer, Club 3D, Diamond Multimedia, Force3D, Gigabyte Technology, Hightech Information Systems (HIS), Micro-Star International (MSI), PowerColor, Sapphire Technology, VisionTek and XFX.AMD Radeon HD 6870 graphics cardPhoto: Company
Apple has unveiled an all new MacBook Air, the first of a next generation of notebooks which will replace mechanical hard disks and optical drives with Internet services and solid state flash storage.Available in 11-inch and 13-inch models and weighing as little as 2.3 pounds, the new MacBook Air is Apple's lightest and most portable notebook. MacBook Air uses the same solid state storage technology as iPad to deliver instant-on responsiveness, up to seven hours of battery life and up to 30 days of standby time.With its precision aluminum unibody enclosure, the new MacBook Air measures 0.11-inches at its thinnest point and 0.68-inches at its thickest, and weighs just 2.3 pounds for the 11-inch model and 2.9 pounds for the 13-inch. Like iPad, MacBook Air was designed from the ground up to use flash storage exclusively. Apple's custom-designed flash storage is 90% smaller and lighter than a conventional notebook hard drive, contributing to MacBook Air's mobile, featherweight design. MacBook Air's flash storage also provides faster data access and is more reliable than notebook hard drives due to its solid state design.MacBook Air features a full-sized keyboard for typing comfort and productivity, as well as the highly acclaimed glass Multi-Touch trackpad found on Apple's MacBook Pro, so you can scroll through web sites, flip through photos, and resize or rotate images all from the trackpad. The built-in FaceTime camera, mic and stereo speakers are perfect for video calls with iPhone 4, iPod touch and other Macs.Flash storage combined with power-efficient Intel Core 2 Duo processors and Nvidia GeForce 320M graphics delivers an ideal balance of mobility, battery life and performance. MacBook Air features an 11.6-inch or 13.3-inch high-resolution LED-backlit display and Mini DisplayPort to connect your 27-inch Apple LED Cinema Display, projector or HD TV. Ultra-fast 802.11n Wi-Fi networking allows you to download music and movies from iTunes, back up data to Time Capsule and store or share files with MobileMe and iDisk. MacBook Air includes Bluetooth 2.1+EDR for wireless peripherals and two USB ports making it easy to sync and charge an iPad, iPhone or iPod while using another device. The 13-inch MacBook Air also includes an SD card slot.Apple uses advanced chemistry and Adaptive Charging technology to create a MacBook Air battery that delivers up to seven hours of wireless productivity on a single charge and up to 1,000 recharges. The built-in battery design results in less waste, and depleted MacBook Air batteries can be replaced for US$129, which includes installation and disposal of your old battery in an environmentally responsible manner.Every Mac comes with Mac OS X Snow Leopard and iLife, Apple's suite of applications for creating and sharing photos, movies and music.The 11-inch and 13-inch MacBook Air are immediately available through the Apple Store, Apple's retail stores and Apple authorized resellers. The 1.4GHz 11-inch MacBook Air with 2GB of memory and 64GB of flash storage starts at a suggested retail price of US$999 with a 128GB model for US$1,199. The 1.86GHz 13-inch MacBook Air with 2GB of memory and 128GB of flash storage starts at a suggested retail price of US$1,299 with a 256GB model for US$1,599. Configure-to-order options and accessories include faster processors, 4GB of memory, MacBook Air SuperDrive and a USB Ethernet Adapter.Apple new 11-inch and 13-inch MacBook Air notebooksPhoto: Company
LED lighting applications are gaining popularity, but a lack of standards is hampering their development in the industry. The DTF Taiwan LED Supply Chain Technology Forum invited Jay-San Chen, director general of the Bureau of Standards, Metrology and Inspection (BSMI) under Taiwan's Ministry of Economic Affairs (MOEA) to give a talk on the issue of LED lighting standards. Chen also revealed his related experiences in China and current cross-strait communication on the subject.Firstly, Chen talked about the LED lighting industry in Taiwan. The MOEA has introduced a green energy industry program. Its goal is to make Taiwan the leading LED light source and module supplier and create 54,000 new jobs. Hopefully, by 2015, the production value of the industry will reach NT$540 billion. In the first half of 2010, the industry generated NT$77 billion in revenues, which is equivalent to 80% of the total revenues in 2009. We expect that the total revenues of 2010 will reach NT$170 billion, with a 79% growth.China's LED lighting industry is heavily subsidized by its government under the 11th Five-year Plan, which allocated 1-1.5 billion yuan for the industry. In addition to the subsidies, the government also helped to set up production bases for semiconductor lighting and removed the non-tariff obstacles. At the same time, it also launched the Lighting Engineering and the 10 Cities with 10,000 Lights projects. It is expected that the above policies will generate 500 billion yuan in revenues and total export value of US$30 billion, and create one million jobs.As for LED lighting standards, Taiwan is working on 21 new standards and amending another. These include three standards for light sources; three for lighting devices; one for photobiological safety; 12 for components and modules; and two for key components. The priority is given to the standards for light sources, lighting devices and photobiological safety, followed by components and modules. The one being amended is CNS 15233 for "LED street lamps," and the revision has been passed and will be announced soon. We hope to gather opinions from the industry during the process of making the standards.The CNS 15233, first announced in December 2008, was the first LED street lamp standard in the world. We expect that the national standards for AC LED issued in 2010 will also be the first in the world. CNS 15233 has also been listed as an item under the CNS certification program, and the LED street lamps made by Everlight Electronics has been granted the CNS logo.In China there are 54 standards for LEDs and 45 for LED lighting. There are 28 national standards, and 71 industrial or local standards. Although it seems that China has more standards than Taiwan, most of them are on industrial levels, which are not as strict as national ones.Taiwan and China have started communication on LED standards. In the fourth meeting between their envoys, Taiwan and China agreed to jointly build a set of cross-strait mechanisms concerning standards, metrology and certification. They will cooperate in five areas: standards, metrology, inspection, certification, and consumer product safety. The MOEA's Bureau of Standards, Metrology and Inspection and China's General Administration of Quality Supervision, Inspection and Quarantine will be in charge of the work.A symposium on cross-strait certification and standards was held in Chengdu, China in July, 2009. China suggested setting up a self-evaluation certification system, and the four group discussions were organized during the symposium to touch on the issues of LED standards, LED evaluation, LED terminology, and LED certification technology. In the coming future, both parties will exchange information regularly and have closer communication. In March 2010, another symposium was held in Fuzhou, China, focusing on the issues of energy saving and new energy. The main themes were 3D displays and photovoltaics (PV). But issues concerning LEDs are expected to be included in the future.A comparison of CNS 15233 and China's GB/T 24827 for street lamps will show that they are similar in performance levels, safety requirements, power factors, protective enclosure levels, vibration and electromagnetic compatibility. The major differences are the standards for temperature cycling (not regulated in China), surge protection, endurance and beam maintenance rate.We have started our cooperation on cross-strait LED product tests, and signed a letter of intent with the Xiamen China National Center for Quality Supervision and Test of Semiconductor LED. We have begun trial runs for semiconductor LED lighting projects. Moreover, we are working with the National Lighting Test Center in Beijing to study and compare LED street lamps' optical and electrical properties. Civilian cooperation has been handled by the Industry Technology Research Institute (ITRI) and the Lighting Association, and they have made a lot progress in different fields since 2006.Jay-San Chen, director general of BSMI Photo: Digitimes, October 2010
Testing is of great importance as most problems occurring during the manufacturing process are related to ineffective testing before production. Jeff Lee, director of Chroma ATE's Integrated System Solution BU, in his analysis of the LED's light, electrical and heat characteristics, noted the key points of testing and introduced some testing methods adopted by the industry.The interaction of light, electrical and heat characteristicsLee began by analyzing the LED's light, electrical and heat characteristics that are interrelated to one another. The characteristics of light include light pattern, light quality and light intensity, and spectrum is the characteristic of light quality. The characteristics of light intensity include luminous flux, luminous intensity, radiation flux and radiation intensity. The electrical characteristics include AC, DC, silicon controlled rectifier (SCR), and electrostatic discharge (ESD). AC and DC include electrical voltage and current, and ESD involves human body model (HBM) and machine model (MM). The characteristics of heat include thermal resistance, heat capacity and heat conduction. We need to run tests in accordance with all these various characteristics.Color rendering index (CRI) is the indicator of the quality of color, and incandescent bulbs have the best CRI at 100 among all light sources. The LED's CRI is not as high in conventional CRI calculation method but the difference is minor for human eyes.Snell's law, a theory that refraction or total reflection occurs when light goes through different mediums, is another consideration in light testing. Measures have to be taken to avoid errors in testing, as in reality a luminous body would be affected by substances nearby.Different chip structures also matter. Chip structures are often upgraded in order to elevate light extraction efficiency, such as truncated inverted pyramid (TIP) that increases the luminous efficacy of red light, or surface roughening and so on.The space between chips also influences measurement. Testing of a multi-chip design would be different from a single-chip one, and the smaller the space between chips is, the higher the luminous intensity will be. The LED's light profile also matters, as the luminous intensity varies with different light profiles even though the luminous flux is the same. Therefore, re-calibration will be needed when testing emphasizes a particular factor. Light uniformity is another problem that needs to be taken care of in testing, because even if there is only one single-chip, the phosphor-excited light still may have uniformity problems and with more chips the differences will be bigger.In terms of LED's electrical property, if uneven curves occur when analyzing LED I-V characteristic due to thyristor effect, forward bias has to be raised to a certain level for the conduction of light, and vice versa, the avalanche current should also be measured.Static can cause damage to LEDs. Sometimes it is due to human contact, and sometimes static discharge from machines sends ESD pulse to the interior of the semiconductor and damages the insulation, which can cause an early disruption of negative voltage. Tests should be done to detect any damage; otherwise LED devices will suffer attenuation as time goes by.In addition, as the LED changes with different materials due to the band gap, wavelength will be different as the band gap decreases with higher temperature.Reference for measurementThe standard for luminous intensity measurement is CIE 127:2007. The included angle will be smaller when measured from a distance, and the specimen under testing will be closer to the point source. Different standards should be adopted for different light-emitting areas. It should also be noted that light is the strongest around the optical, instead of mechanical center of the specimen under testing.The calculation of luminous flux, if done at every angle with a sensor, is very time-consuming and costly, so it can be calculated by using integrating sphere. As the distance and size of partial flux's opening will affect test results, there are strict rules in this regard. In addition, illuminance can be worked out with relative area figures when measuring radiant flux density and irradiance.The measurement of electrical characteristics is under the influence of thyristor effect that was first used by the US military and applies to all PNPN semiconductors because LED phenomena are similar to thyristor's. The reference standards in use now are: MIL-STD-750E Method 4026.3: Forward recovery voltage and time; and Lumileds' Application Brif AB22 Test Conditions For P3 series TS AlInGaP LED Chips.ESD requires various tests in accordance with the causes, and MM is used to simulate the electro-static discharge protective ability when the machine touches the components in the fabrication process. The standards include ESDA STM5.2, JEDEC EIA/JESD22-A115 and Q100-003-Rev-C. HBM simulates the components' electro-static discharge protective ability to human bodies, or the human bodies' to the components. CDM simulates the components' protective ability against ground discharge. All these have their own standards.Jeff Lee, director of Chroma ATE's Integrated System Solution BUPhoto: Digitimes, October 2010
LED heat dissipation is a much more serious issue than thermal conductivity to the extent that it remains a major bottleneck for systems so far. With in-house developed technology, TeamChem has invented a flexible ceramic thermal conductive adhesive to replace traditional thermal conductive adhesive and the anodizing process. Todd Yeh of TeamChem's R&D unit elaborated on the problems of thermal conductivity and heat dissipation as well as applications of the company's products.Thermal conductivity and heat dissipationThermal conductivity and heat dissipation are just like traffic problems. Germany has a relatively big population. The country has a sizeable population in its suburban areas partly because there is no speed limit on its highway. However, highways without speed limit can still suffer traffic jams due to poor interchange design. Both factors have to be taken into consideration to achieve smooth traffic and better commuting experience.Thermal conductivity and heat dissipation are two different concepts. For LED, substrates act as a thermal conductor instead of a heat dissipater, since heat dissipation means spreading heat into the air. As heat dissipation is a bigger issue than thermal conductivity, the 5W and 10W thermal conductive substrates commonly seen now actually are approaching the issue in the wrong direction and often turn out to become bottlenecks.Conventional thermal management methods include fans and heat sinks. But these are not applicable to LEDs. Fans, with their problems of energy conservation and dust accretion, reduce the durability of LEDs, while heat sinks are less effective. We still need to find better solutions to LEDs' heat dissipation problem.What are the possible solutions? Should we resort to air flow, increase the surface area or reduce the mass (thickness) in order to decrease heat storage?It is generally believed that a higher k value means better thermal conductivity, but thickness is often not taken into consideration. Thermal impedance will decrease with lower thickness, and heat dissipation can only be completely achieved with low thermal impedance.For traditional MCPCB, the thickness measures more than 1,600µm, with 35µm of copper foil, 100µm of adhesive and 1,500µm of aluminum plate (their k values are 400, 1 and 200W/m-K, respectively). The thermal impedance results are 0.1, 100 and 7.5µm2-K/W, respectively, adding to a total of 1.08cm2-K/W thermal impedance. This is actually the whole picture of MCPCB's heat dissipation performance. Thermal impedance measurements of several commercialized MBPCBs range from 2-4c m2-K/W.However, as the aforementioned figures are the sum of individually-calculated thermal conductivity measurements from three different layers, problems may occur in the future if interfacial thermal impedance rises. Moreover, the substrate surface needs to be filled by liquid because it is uneven from a microscopic view. Whether the surface of the thermal conductive board (TCB) can become totally even is one problem, and aluminum plates often suffer inconsistent heat dissipation.As for heat dissipation, its measurements involve still air and moving air, as air is the source of thermal impedance. Thermal impedance in still air ranges from 400-3,000cm2-K/W, and 200-1,000 cm2-K/W in moving air. You can multiply these thermal impedance figures.LED-related applications have their own heat-dissipation characteristics. For example, as there is no moving air to accelerate heat dissipation without fans, thermal impedance will be pretty high around 1,000cm2-K/W in still air. The fact that the surface temperature of most substrates is kept below 60 degrees Celsius is also a major limitation in need of solutions. Besides, while heat dissipation does represent a bottleneck, thermal conductivity is not much a problem in comparison.A number of factors must be addressed in order to promote growth of the entire LED industry, including lower costs, simplified structures and assembly processes, and better thermal management and reliability. These can all be achieved with the introduction of new materials such as low-cost thermal conductive FPCB (while aluminum costs are four to five times higher), low-temperature-curable silver conductive adhesive, and optically clear thermosetting adhesive film.Trends in product applicationsTeamChem's flexible ceramic thermal conductive adhesive - a waterproof, antistatic and self-cleaning material with high tolerance pH range of 3-11, insulating properties, weatherability and great heat dissipation - can be used for outdoor LED lamps. According to tests by clients who are LED lamp makers, system temperature is lower than traditional treatment by 10 degrees Celsius, and 7 degrees Celsius lower than anodizing treatment. The cost is also low at below NT$90 for every square meter of TC-19E thermal conductive spray coating.Conventional LED aluminum substrate fabrication is a time-consuming and costly method using copper foil, multi-layer thermal conductive adhesives and aluminum plates before anodizing the lower part of the substrates. The new fabrication method also requires cooper foil and aluminum plates but there is only one layer of thermal conductive adhesive, and the thermosetting, high-temperature-resistant, shockproof TC-19EW coating can be easily spayed and effectively bring down the temperature. The material is also acid/alkali resistant, anti-static and can prevent dust from sticking to the surface.Other applications include large thermal conductive aluminum plates for LED TVs, capacitors, or various devices, such as motors, heat exchangers, transformer boxes and internal combustion engines, that generate heat and may be exposed to natural elements.Todd Yeh of TeamChem's R&D unitPhoto: Digitimes, October 2010
Thermal issue has always been a key part in the development of the LED industry. Polytronics Technology offers aluminum substrates as the best solution for edge-lit LED TVs. Yi-An Sha from Polytronics is optimistic about the growth of LEDs' application in backlighting and general lighting. He discussed the technological development trend of thermal substrates and analyzed the pros and cons of different technologies.The trend of backlighting and lighting marketThe market trend of LED replacing CCFL is obvious. Taiwan's top CCFL manufacturers are gradually turning their focuses to LED-related products, whose share of their revenues has reached 52%. Meanwhile, the proportion of revenues from CCFL products has come down to 42%. LED backlighting is applied to various LCD panels, using such backplanes as FPCB (screen size below 15 inches), MCPCB (screen size above 15 inches, mostly edge-type) and FR4 (screen size above 6 inches, mostly direct-type).According to DisplaySearch, the penetration rate of LED backlighting in the notebook market is estimated at 90% in 2010 and 100% in 2011. In the LCD monitor market it is estimated at 25% in 2010, 50% in 2011 and 85% in 2016. In the large-size TFT-LCD market it will reach 50% in 2011 and 80% in 2012. Now the sales of LED TVs are facing short-term fluctuations mainly because of price differences, inventory digestion of CCFL sets, and adjustments in LED-backlit product lineups.As for the cost of LED TVs, the edge type is cheaper than the direct type. In the case of edge type, to further reduce the cost of backlighting, the amount of LEDs and light strips has to be reduced. Meanwhile, the brightness of LEDs, the light extraction efficiency and heat dissipation of modules need to be improved as well. Heat dissipation can be improved by using high thermal conductive board (TCB).IEK estimates the LED lighting market will reach US$5.2 billion in 2012, and its compound annual growth rate (CAGR) from 2007 to 2012 will reach 28.5%. At present LED lighting is mainly found in architectural, industrial and commercial applications. The LED streetlamp sector now embraces the concept of Energy Performance Contracting (EPC), which came into existence amid the energy crisis in the 1970s. The proprietor does not have to pay, while the supplier earns from the price difference resulting from energy savings. For the supplier, the better their technical capabilities, the more their profits. But they need to keep considerable capital in the short term.Industrial application and technological developmentThe trends of industrial application and technological development include brightness enhancement, optical improvement, energy saving, product reliability and reduction of cost. Among them product reliability is highly related to heat dissipation. The key issue of LED heat dissipation is to provide thermal conductive media to transfer the heat from the LED to the thermal substrate and then to the thermal module. If the base area of the LED is widened, then the area of heat dissipation will increase. Power supply is needed as well. The materials for composing thermal substrates are related to three areas: copper foil electric circuits, ceramic powder plus macromolecules, and aluminum substrates. The thermal conductivity of ceramic powder is 20W/m-K, macromolecules is 0.1W/m-K, and FR4 is 0.36W/m-K.Heat dissipation materials include fused silica (SiO2), aluminum oxide, crystalline silica, silica, aluminum nitride, and boron nitride. Fused silica and aluminum oxide are low-cost, and aluminum oxide has high thermal conductivity of 30W/m-K; so they are the main stream in the market. Aluminum nitride has the best thermal conductivity of 320W/m-K, but costs are high and reliability is low.Glass-fiber thermal substrates are made with macromolecules, high thermal conductive ceramic powder and glass fiber cloth. The advantages of glass-fiber thermal substrates are their easy manufacturing process, better thickness uniformity and low production costs. Their disadvantages include: good thermal conductivity on the Z axis but bad on the X-Y plane; and serious warpage.As a kind of traditional PCB, FR4 is often used in low-power electronic components or LEDs. Its thermal conductivity is merely 0.36W/m-K, therefore lower reliability. Its disruptive voltage is around 40KV/mm and price is low. Ceramic thermal substrates are suitable for high-power LEDs or electronic components. They have thermal conductivity of 2-12W/m-K and thus are more reliable. Its disruptive voltage is around 60KV/mm, but the price is three times that of FR4.Technological development of metal thermal substrateThere are two ways to produce metal thermal substrates: the dry process and wet process. The former is processed with macromolecules through continuous injection, and no solvents are needed, which reduces pollution. The latter is simple but has lower reliability. It uses solvents for blending and its chief process is printing (screen or blade printing), which needs to be dried.Polytronics' high thermal conductive silicon film adopts the "roll-to-roll' continuous dry process. It is the only 12W/m-K thermal film roll in the world. Its dry process is environmentally friendly.Yi-An Sha from PolytronicsPhoto: Digitimes, October 2010
